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Chapter XIX of the United Nations Charter
deals with ratification and signature of the UN
Charter. It provided that the Charter would enter into force once
ratified by the Permanent Five members of the UN Security Council and a majority of the
other signatory states. The Charter was opened for signature on 26
June 1945 and entered into force on 24 October 1945, which became
known as United Nations Day. In the meantime,
the atomic bombings
of Hiroshima and Nagasaki took place on August 6 and 9,
respectively; the introduction of this new weapon of warfare
completed changed the security environment in which the UN Charter
was promulgated.